A HIGH-PRECISION SYNCHRONOUS SAMPLING APPROACH FOR LARGE-SCALE DISTRIBUTED WIRE SENSOR NETWORKS IN SEISMIC DATA ACQUISITION SYSTEMS

In large-scale land or marine seismic data acquisition systems, a multinode distributed wire sensor network structure is still presently the main choice. Synchronous sampling between each node in such systems is very important, which may significantly influence the results of the ensuing data analysis. A synchronous sampling approach with its implementation is introduced in this article. The main idea of this approach is combined command delay compensation with clock phase compensation of CDR (clock data recovery) to achieve high precision of synchronization. For testing, a kind of six-node land seismic data acquisition system with 100 m distance between two neighboring nodes is successfully developed using this approach. Test results indicate that the achieved precision of synchronous sampling is fixed after power-on with no time accumulation effect; the sampling clock phase difference between two neighboring nodes is maximally 1 ns in the worst case, and the command synchronization error among all the nodes is less than 1 ns independent of the number of nodes and the distance between nodes. High synchronous precision is much more significant for the shallow stratum engineering seismic exploration, because shallow exploration always needs high sampling rates; for example, 32 kilo sample per second, and hence the tolerant synchronization error is much smaller.